A message on the site says it has been compromised by a security exploit
High-profile tech blog TechCrunch is back online after being hit by hackers.
The site, which profiles Silicon Valley start-ups and US firms, was offline for nearly four hours from 0630 GMT.
TechCrunch said that it had been "compromised by a security exploit" but was still "gathering information" as to how it had happened.
The site went down at around and was replaced by various messages including a link to a site directing people towards adult material.
Graham Cluley of security firm Sophos said in a blog post: "There's no such time as a 'good time' to be hacked of course, but one can only imagine that today is a better day for TechCrunch to be hacked than tomorrow when the site will, presumably, be expecting a large amount of traffic."
Apple is expected to make an announcement about a new product on Wednesday - possibly a tablet computer - which TechCrunch will closely follow.
"This hack is a salutary warning to all website owners that everyone has to be on their guard against hacking, whether your site is big or small," said Mr Cluley.